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Option B: Food science
Biotechnology and food
production…read more

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Specification objectives
Understand that microorganisms
(bacteria and fungi) can be used to
modify foods as illustrated by the
conversion of raw cabbage to
sauerkraut, milk to yoghurt and soya
beans to tofu and soy sauce
Explain the changes in pH in relation
to storage.…read more

Slide 3

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Biotechnology is any technique which
uses living organisms or their
components to make or modify
products, to improve plants or animals
or to develop micro-organisms for
special uses.…read more

Slide 4

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Cabbage can be
fermented by bacteria
under anaerobic
conditions in the
presence of salt to
produce sauerkraut.
Mature cabbage
heads are used, with
a sugar content of 2.9
to 6.4 per cent…read more

Slide 5

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How to make sauerkraut
the ideal is
The lactic between 21
acid and 24°C
bacteria are
The shreds are
favoured by mixed with 2.5 per
the salt
Leuconostoc ferments the
cent by weight of
conditions glucose and lactose in the
salt and packed
The temperature cabbage to lactic acid and
into a vat,
needs to be kept carbon dioxide is given
weighted down and
The cabbage off. Lactobacillus then
covered closely. above 15°C
is washed in uses some of the by-
clean water products, increasing the
and shredded lactic acid content to
to increase its No starter culture about 1.7 per cent
needs to be added
surface area as the fermentation
is carried out by
bacteria already
immersed in brine. present on the Respiration of both
that the shreds are cabbage. the bacteria and the
of the cabbage, so
draws moisture out
cabbage uses up 30 days
to escape. The salt the available n takes 20-
during fermentation The pH of the finished oxygen, so that
conditions become
allow gases produced
the seal needs to product is about 3.5.
anaerobic.…read more

Slide 6

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Yoghurt is a dairy
product produced by
bacterial fermentation
of milk.
Any sort of milk may
be used to make
yoghurt, but modern
production is
dominated by cow's
milk.…read more

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